I used to use Opera back in the days when Mozilla was the big bloaty browser and Phoenix wasn't around. It wasn't the greatest browser but it was certainly better than IE, although you had to use IE quite frequently for sites which only worked in IE - nobody even considered other browsers with IE being so dominant.

However after using so many plugins in Firefox, even though it probably isn't quite as fast as Opera I still prefer it. Hopefully Firefox 3 will turn Firefox into an even faster browser.

I've tried going back to Opera for the improved performance, but could never quite get used to some of the minor quirks which you just can't change.